When to Plant Sunflower in Le Sueur County, MN
Your May planting checklist for Le Sueur County, Minnesota
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Le Sueur County, Minnesota.
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Plant out sunflower
Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.
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Seed sunflower outdoors
Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.
Sunflowers are tall, cheerful annuals grown for their edible seeds and as pollinator magnets. They come in sizes from 2-foot dwarfs to 12-foot giants.
Le Sueur County, Minnesota is in USDA Zone 4b. The average last spring frost is April 30 and the first fall frost is October 3, giving you a growing season of approximately 156 days.
At an elevation of 628 feet, Le Sueur County receives approximately 41.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Sunflower to ensure they mature before fall.
Le Sueur County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-7.3
Drainage
Well Drained
Plant Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Soil Compatibility in Le Sueur County
How your county's soil matches Sunflower's growing requirements.
Soil pH
Your soil pH (5.9–7.3) overlaps with Sunflower's range (6.0–7.5), though not a perfect match.
Soil Texture
The silt loam soil in Le Sueur County is excellent for Sunflower — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.7%) — Sunflower will thrive.
How to Plant Sunflower
Succession Planting Sunflower
Sow every 8 weeks. Last sowing by Jun 25 to harvest before frost.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Sunflower
Sunflower needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Sunflower Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 2.1" | 0" | ❄️ Dormant |
| Mar | — | 2.7" | 0" | ❄️ Dormant |
| Apr | 2.2" | 4.4" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 4.4" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4.9" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 5.4" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 4.6" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.9" | 0" | ✅ Rainfall sufficient |
| Nov | — | 3.2" | 0" | ❄️ Dormant |
| Dec | — | 2.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Le Sueur County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Sunflower Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Sunflower Planting Timeline — Le Sueur County, MN
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 26 | Feb 26 – Mar 12 |
| Transplant Outdoors | May 21 | May 21 – Jun 4 |
| Direct Sow | May 14 | May 14 – Jun 4 |
| Harvest | July 30 | Jul 30 – Sep 17 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 4b
📆 Growing Season
156 days in Le Sueur County
Growing Tips for Sunflower in Le Sueur County
Direct sow Sunflower outdoors after April 30 in Le Sueur County when soil has warmed and frost danger has passed.
Common pests for Sunflower in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow after last frost. Stake tall varieties in windy areas. Harvest seed heads when the back turns brown and seeds are plump. Dry heads upside down.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Sunflower in Other Locations
Frequently Asked Questions
When should I plant Sunflower in Le Sueur County, MN?
Le Sueur County is in Zone 4b with an average last frost of April 30. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Le Sueur County, MN?
Le Sueur County, Minnesota is in USDA Hardiness Zone 4b. The average last spring frost is April 30 and first fall frost is October 3.
Your Le Sueur County Garden Planner — Free
A 24-page printable planner built for Le Sueur County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.